How do we observe today's climate?

People from all walks of life use thermometers, rain gauges, and other instruments to keep a record of their weather. Additionally, automated networks of scientific instruments monitor weather and climate at all hours of the day and night, all around the world. The instruments used to measure weather range from simple, physical devices to complex instruments, such as those attached to satellites.

Why Pay Attention to Weather?

For as long as humans have been around, they've paid attention to weather and climate. They noted the type of weather brought by winds from particular directions and watched for different types of clouds in an attempt to predict upcoming weather. Some people who spend a lot of time outdoors can still recognize insect, bird, and animal behaviors as signs of changing weather. All around the world, local climate influences how people live. The types of homes we build for comfort and safely, the crops we grow for food and clothing, and the recreational opportunities we enjoy are all matched to our long-term weather patterns. We strive to understand and predict the weather in order to better our lives.

Early Weather Records

Explorers and pioneers often described their daily weather in handwritten journals and logbooks. As scientists invented reliable, affordable weather instruments and communication and data recording methods improved, people participated in group efforts to collect and share their records of weather. In one example from the early 1800s, an Army physician who was interested in the relationship between weather and the health of the troops ordered a systematic effort to collect weather data. Soldiers at army posts across the country observed and recorded their daily weather and sent their records to a central location. This effort eventually resulted in more than twenty years of systematic weather records for a large part of the country. In 1891, the task of monitoring weather was transferred from the military to a civilian corps, creating the agency we now call the National Weather Service (NWS).

Monitoring Weather at the Surface

Over time, scientific organizations began establishing networks of weather-observing stations across the country and around the world. The United States has thousands of official weather stations, and many more volunteer observers who record weather data every day. At many stations, observers have collected a continuous record spanning several decades. Some other stations only operated for a few years before stopping. Weather stations where data were collected for some period include:

Monitoring Weather from Above

Climate monitoring instruments
Image source: NOAA, USGS, and NASA

Just as ground-based weather instruments improved over the years, so too did our ability to measure weather at various heights above the surface. Early methods of monitoring weather from above included the use of kites, balloons, and airplanes. Today, we have a large number of satellites with specialized sensors orbiting the planet, monitoring our weather from miles above.

What Variables Do We Monitor?

How do we know climate is changing? Which variables help us understand climate and detect climate change? An international group of meteorologists and climate scientists have agreed upon a list of essential climate variables (ECVs), that we monitor to help us understand changing conditions. ECVs were selected based upon their feasibility, relevance, and cost-effectiveness, as well as their reliability and consistency. The variables are grouped into three categories: atmospheric (air), terrestrial (land), and oceanic (ocean). For all categories, sensors record both in-situ (in place) and remote measurements.

To learn more about the specific variables we monitor and the instruments we use to measure them see:

Where Do All These Weather Data Go?

Super computers are used for storage of climate records.
Image source: NCEI

As our abilities to record weather observations matured, scientists and government administrators recognized the value of gathering and storing these records in a single place. In 1951, they established what is now called the National Centers for Environmental Information (NCEI). Official weather records—ranging from observers’ handwritten logbooks to early computer tapes to real-time measurements from our array of automated weather stations—are stored at this center. Today, many of these records have been or are being digitized through citizen-science efforts. NCEI makes these records available to the public via the Internet.